Air cleaner



Jan. l0, 1950 Filed May l5, 1945 A. H. BAHNsoN, .JR

AIR

Jan. 10, 1950 A, H. BAHNSON, JR 2,493,849

AIR CLEANER Filed May 15, 1945 2 Sheets-Sheet 2 Patented Jan. 10, 1:95,()

UNITED STATES PATENT l OFFICE 2,493,849

Am CLEANER Agnew H. Bahnson, Jr., vWinston-Salm, N. c.

Application May -15, 1945; Serial No. 593,788v

In the operation of Ventilating and air conditioning systems it is frequently desirable and sometimes practically necessary to lter the air to remove suspended dust, lint, insects and other suspended solid impurities from it. This is particularly true in factory or work shop systems the room.V The former may not require filtering.

but the latter generally does.

The present invention relates to apparatus for filtering the air in such a Ventilating system and is particularly adapted for use with the ventilating system of a textile mill in which the suspended solid impurity in the air consists principally of lint.

The outstanding problems presented inthe.

provision of means for cleaning the air of a ventilating system for a textile millis to provide a filter that will continuously and efficiently re move the suspended solids from the air .and will handle a large volume of air without unduly burdening the air circulating means.

The accompanying drawings illustrate anem-4 bodiment of my invention.

Referring to the drawings: v Fig. 1 is a fragmentary horizontal sectional plan view of the air filter associated with a duct* for supplying fresh and recirculated air to arroom; Fig. 2 is a front perspective elevational viewofthe iilter; A Y

Fig. 3 is a fragmentary vertical end elevation of thelter in one operative position and;

Fig. 4 is a fragmentary ver-tical end elevation of the filter in another operative position.

In the embodiment illustrated in Fig. 1 theA filter ispositioned to filter only the recirculated air but it is to be understood thatvthis is merely illustrative and-that .the filter may be positioned to lter only the fresh air or both the fresh and'. the recirculated air or that a battery of the filters;

may. be arrangedto lter the air aty a central station. V-

In Fig. 1 the Ventilating conduit or duct comprises the branch I leading to a source of fresh 2. air,lsaid branch beingL controlled by dampers 2, a branch 3 leadingto the iilter 4,.said branch 3 beingcontrolle'd by dampers 5, and a branch 6 leading into the space to be ventilated,` said branch 6 containing .the fan or blower 1 and humidifier 8 both driven by the motor 9.

vThe iilter consists 'of a cylindrical screen of suitable mesh, preferably as fine as fly screen, i. e. about 15 mesh to the lineary inch or finer, smoothly supported up'ona ,cylindrical cage like structure (not shown). Thefscreen supportmay consistfor instance of end-rings carriedby radical spokesy from hubs with longitudinal ribs supportedfbetween the ,.Itwo rings Vand preferably, in; order smoothly to support-the fine wire screen, oircumferenti-albands or a-relatively coarse and rigid screen supportedon the rods and serving to carry the ,relatively iiexible ne wire screen. So far as my vpresentV invention is .concerned the iilter is merely a.,h'o11o w cylindrical fine wire screen open .at one'v endland closed at the other. and mounted forA rotation on a substantially horizontal axle, .such as one skilledV in the art might produce following thisfbrieffgeneral description.

vThefopen. end of the cylindrical screen communicates. with the-branch 310i" the Ventilating conduit and issealed thereto -inany suitable way as to providinga smoothimperforate band around the open end of thecylinder against which bears a iiexblel sealing .member such as a cloth or fabric ring carried by. the vwalls ofthe branchy 3. It will be appreciated. that the cylinder rotates while thebranch 3ofl4the Ventilating conduit is stationary yand means Amust befprovided for prenoty critical.

venting too.-nfuch.airfromby-passing the screenand enteringthe branch 3 directly without passing through thescreen. Some leakage between the screen andthe Ventilating conduit is of course The.closed end-,of the` cylindrical filter is provided with. anA external-ring gear |01 which meshes with the pinion l lvdrilven .bythemotor I2 through suitableV reducing gearsf` I.f3-.

The`- dofngbox l4- encloses about the lower front quarter.ofthebylindrical screen and serves .to house `the mechanismlfor cleaning-the screen and also as a receptaclefor the accumulated dust.

Referringto Fig. 3 twill be seen that substantially the lowerv front quarterv of the screen i. e. substantially that portion covered by the box Misback'ed bythe stationary imperforate baffle I5 supported paralleltotheinside of the screen by the radial armsl lli.V 'Arms IGaresupported by the.stationary..axle.,ilv vuponV .which the lcylinder rotates. Each edge of the baille l5 is sealed to the inner side of the screen, the upper edge by brush I8 or a rubber flap or other suitable iiexible sealing member and the lower edge by brush I9. The upper arms I6 are provided with slip holes so that the baille I is pivoted about its connections to the lower arms I6 and the spring 2U attached to the upper edge of the balile tends to tilt it and to hold the brush I9 snugly against the inner surface of the screen.

A radial portion of the cylinder, about GQ of the circumference thereof, is imperforate and the leading edge of the imperforate portion of the cylinder carries the brush 2I which projects outillustrated merely the timer 3| to indicate that the operation of the cylinder is to be regulated.

The door 32 of the box I 4 is normally closed. As the screen cylinder 4 rotates and dust laden air is drawn through its exposed surface by the fan 1, a filter cake accumulates on the surface and the surface bearing thisrfilter cake passes in contact with the doiiing cloth 24. The lter cake is thus rolled oli of the screen surface and dropped into the box It where it collects.V During the action of the dofng cloth on the screen surface the screen is backed by the baffle I5 which .lprevents the dust loosened from the screen by wardly from the surface of the cylinder. `The I.

purpose and function of the brush 2I is to prevent the accumulation of a wad of dust or lint. between the doiiing cloth and the cylinderas willv be'described below. At the ends'of'the'brush 2l thedoffing cloth from being sucked through the `screen and passing with the filtered air through 1 the branch '3 into the Ventilating duct.

and also carried by the cylinder are the cam meme r bers 22 the purpose ofgwhich is to raise the doiiing cloth away froml the cylinder-.while the brush 2I passes. A brush 23 is springmounted to bear against the outer surface of the .cylinder andv its 'supporting structure at each end thereof is provided'with the cam surfaces v33 adapted to engage the cam surfaces'22 and thus toralse the brush 23 clearof thesurface of the cylinder and to permit the brush'ZI to pass. The principal purpose oftheV brush 23 is Vto clean the Vouter surface of the screen. Incidentally Yit serves to cleanthe brushf2| and to seal the opening between the screen and the lower edge of the box I4. 'The doiiing cloth 24 is secured by the upper edge thereof to the 'stationary rod 25 and extends downwardly over the cylinder surface to the weight 26.,` The domng cloth is normally `held against the surface of the cylinder by the longitudinal rods 21 and 28 supported by the arms 29 hingedon the rod `25"and normally pressed toward the cylinder by the spring or springs 30.

The operation of the filter is as follows.: It isi rotated at a suitablerate, depending 4upon the amounty of air being filtered and the'amount of dust which it contains, by the 'motor' I2. The filter functions to clean the air most perfectly when it carries a layer of filtered lint, said layer serving more perfectly than the fine mesh screen to vfllter'iine dust particles out of.v the air.1 In the movement offa given point of the `surface of the cylinder from the point where it is cleaned through-the branch, 3 or tothe 'pressure'in' the branch 3 by theuse of 'a suitable gas velocity or pressure responsive instrument. The flow or pressureresponsive in'strurnent'mayY act either to control an electrical switch to stop 'and start theVV motori or to operate speed control mechanismY to vary-the speed of the motor. Thus when the pressure or flow rate exceeds a certain figure, the cylinder'may be stopped orslowed andwhen the pressureor rate of iiovvr drops the motor may beV started or caused to run faster.V Suchl details of the control of the` operation of the cylinderare within the skill of a 'mechanic Vor Qelectricianand are not illustrated or `j described `in detail. I have tatedbythe raisingof the Vrods28 and 2I'by the,y cams 22. The dust stirred up by this operation'` also'is prevented from passing through the iilter into Athe Ventilating air by thebaiiie I5. If the box were perfectly'rtight, the baiile I5 wouldV be .un`

necessary because thenthere would be no movement of airthrough the scren wihin h box and within thebox but the box is not sealed to the screen sulilciently tightlyrto prevent some move? ment of air through the screenrwithin the box and the bafie I5 therefore serves a useful purL pose. That portion of the cylinder which is not' engaged by the doiiing cloth` i. e. that portion ofY the cylinder which passes the doing cloth while' the latter is raisedV clear of the cylinder by the cams 22 preferably is irnperrfprate.Y However'since very little ,air` passes through that portion of the` screen within the box due t0v the action ofthe box and the baille it is not essential to have this section of the cylinderfimperforate, this: being merely an addedrefinement.V

' The dust, and lint accumulated in the boxv I 4 is removedV from time to time through thev door;

The useV of a revolvingscreen for filtering theY air of va Ventilating or air conditioning system,

and the use ,of a doiiing cloth for cleaning the surfacev of the screen is disclosed in a patent to Agnew H. Bahnson, No. 2,178,463 and in a patent to Jerry H. Sirnpson,.No.I 2,169,435. `My present' invention is concerned with improvements of this Y previously disclosed apparatus, particularly with respect to theprovision of means for the removal of'acc'umulated lint from between the cylinder and the doliing cloth,r for preventing dust stirred up or released bythe cleaning operation from'passingthrough the screen into the filtered air, and for keepingthe screen clean,'that is,

for preventing lint and dust from packing in' of the cylinder and a brusncarried by the 'cylin'y der and extending outwardlyfrom the outer surfV face thereof and'serving to remove the mass of filtered material accumulated bysaid sheet ofV fabric. Y

2. An air filter comprising a hollow cylinderr havingav filteringcylindricalrwall, means for re" volving thecylinder, means for passing air to be amante.

filtered inwardly through the cylindrical wall, a sheet of fabric yieldingly held against the outer surface-of the cylindrical wall; ka stationary'brush positioned' torbear against the outside ofv the cylinder and.'yieldingly` held against the cylinder, a brush carried bythe cylinder andiextending outwardly from the-outer surface thereof to engage and*`v clean said. sheet .of fabric andA means carried by the cylinder forraising said yieldingly held brush away from the sur-face of the cylinder to permit the passage thereunder of said brush carried by the cylinder said. brushes engaging-.each other. in passing whereby. theyare; cleaned. 1

3. An air cleaner comprising a hollow cylinder having a filtering cylindrical Wall, means for revolving the cylinder, means for passing air to be filtered inwardly through said cylindrical wall, a stationary imperforate baille supported within the cylinder and adjacent the inner surface thereof, said baille extending over a segment only of said cylindrical surface and serving to hinder the passage of air through said segment of the cylinder wall, yielding means for sealing the edges of the baffle to the cylindrical wall and a cloth yieldingly held against the outer surface of the cylinder opposite said baille.

4. An air cleaner comprising a hollow cylinder having a filtering cylindrical wall, means for revolving the cylinder, means for passing air to be filtered inwardly through said cylindrical wall, a stationary imperforate baille covering a segment of the inner surface of the cylindrical wall, a

cloth yieldingly held against the outer surfaceV of the cylindrical Wall opposite said baille and a brush carried by the cylindrical wall and eX- tending outwardly therefrom and serving to remove filtered material from said cloth.

5. An air cleaner comprising a hollow cylinder having a filtering cylindrical wall, means for revolving the cylinder, means for passing air to be filtered inwardly through said cylindrical wall, a stationary imperforate baille covering a segment of the inner surface of the cylindrical wall, a cloth yieldingly held against the outer surface of the cylindrical wall opposite said baille, a brush carried by the cylindrical wall and extending outwardly, and means carried by the cylinder for raising said cloth away from the surface of the cylinder to permit the passage thereunder of said brush.

6. An air cleaner comprising a hollow cylinder having a illtering cylindrical wall, means for revolving the cylinder, means for passing air to be filtered inwardly through said cylindrical wall, a stationary brush bearing against the inner surface of the cylinder, a brush yieldingly held against the outer surface of the cylinder, a cloth yieldingly held against the outer surface of the cylinder, a brush carried by the cylinder and extending outwardly from the surface thereof and means carried by the cylinder for raising said cloth and said yieldingly held brush away from the surface of the cylinder to permit said brush carried by the cylinder to pass.

'7. An air cleaner comprising a hollow cylinder having a filtering cylindrical Wall, means for revolving the cylinder, means for passing air to be nltered inwardly through said cylindrical wall, a brush yieldingly held against the outer surfaces of the cylinder, a cloth yieldingly held against the outer surface of the cylinder, a brush carried by the cylinder and extending outwardly from the surface thereof and means carried by the cylinder for raising said cloth and said yieldingly heldk brush away from the surface of the cylinder to "ill permit said brushrcarriedrby the cylinderto passA 8. An air cleaner comprising ai cylindrical wall having a longitudinally: extending imperiorate segment, andi ai longitudinally extending foraminous filtering-segment, means supportingsaidi cylindrical wall-for r'otation'bn its axis, one end ofthe space: enclosed by saidcylind'rical wall being closed andthe: other end being! open, means for rotating said cylindrical: wallonfits axis; means for passing airto: be ltered inwardly through the filtering segment of said wall and for withdrawing the resulting filtered air from the space enclosed by saidwall. throughsaidropen end, a stationary baille covering a. segment of the inner surface of said Wall and preventing the passage of air therethrough, the edges of said baille being sealed against the inner surface of said Wall by flexible sealing means carried by the edges ofthe baille and bearing against the wall, the sealing means along at least one longitudinal edge of the baille being a brush, a sheet of fabric, means for yieldingly holding said sheet of fabric against the outer surface of said Wall at a position opposite said baille, a brush carried by the imperforate portion of said Wall and extending outwardly therefrom, a stationary brush positioned to engage the outer surface of said wall adjacent said baille, means yieldingly supporting said stationary brush in contact with the outer surface of said wall, cam members carried by said wall and positioned to engage the means yieldingly holding the fabric against the wall to move the same away from the Wall and permit the passage thereunder yof the brush carried by the wall, said cam means also engaging the means yieldingly supporting the stationary brush against the wall to move said stationary brush away from the wall and permit the brush carried by the wall to pass under it and a box enclosing said fabric and said stationary brush for receiving dust and lint removed thereby from the surface of the wall.

9. An air cleaner comprising a hollow cylinder having a ltering cylindrical wall, means for revolving the cylinder, means for passing air to be filtered inwardly through said cylindrical wall, a stationary imperforate baille covering a segment of the inner surface of the cylindrical wall, a cloth yieldingly held against the outer surface of the cylindrical wall opposite said baille, a brush yieldingly held against the outer surface of the cylinder, a brush yieldingly held against the inner surface of the cylinder, and means for raising the cloth and also said brush yieldingly held against the outer surfaces of the cylinder.

10. An air iilter comprising a hollow cylinder having a filtering cylindrical wall portion, means for revolving the cylinder, means for passing air to be filtered inwardly through the ltering cylindrical Wall portion, stationary cleaning means positioned to bear against the outer surface of the cylinder and yieldingly maintained in contact therewith to' remove filtered material from the filtering surface, and a brush carried by said cylinder positioned to engage said stationary cleaning means upon rotation of said cylinder whereby to remove illtered material therefrom.

11. An air filter comprising a hollow cylinder having a filtering cylindrical wall portion, means for revolving the cylinder, means for passing air to be filtered inwardly through the filtering cylindrical wall portion, a stationary brush positioned to bear again the outer surface of the cylinder-,and yieldingly maintained in contact therewith to remove ltered material from the le oi this patent:

NIT'DSTATES PATENTS filteringsurface, and a Vbrush carried by 'said Number Y Name Date cylinder positioned to engage said stationary 360,129 Whtehill Mar- 29, 1837 brushupon rotation of said cylinder whereby to 5 '399,713 Watson Mar. 19, 1889 remove ltered material collected by said sta- 796,434 Klein Aug. 8, 1905 tionary brush, the engagement of said brushes 1,444,092 Anderson Feb. 6, 1923 with each other in passing, effecting a mutual 2,169,435 Simpson Aug. 15, 1939 cleaning thereof. 2,178,463 Bahnson Oct. 31, 1939 AGNV'EYW BAHNSON, JR. 10 FOREIGN PATENTS .Y Y REFERENCES CITED Number Country Date Y The following references are of record in the 740,118 France NOV' 12 1932 

